DVD-164C Component Color Codes - IPC Training Home Page

DVD-164C TranscriptSubstitutionsOur final topic involves component substitutions. There may be times when the component weneed to make a repair with is out of stock. If this is the case, it may be appropriate to substitute acomponent with similar characteristics. Always refer to your company policy for substitutingcomponents. Be aware that some companies never allow substitutions. When substitutingvoltage, wattage or tolerance, check the Bill Of Materials for the complete description of thecomponent. It’s important to realize that exact matches are not always necessary. Here are somegeneral rules for substituting components.Voltage can be substituted with a higher voltage but not lower. Voltage is the potential energythat makes electricity flow in a circuit. For example, if the bill of materials calls for a 50 voltcomponent – a 100 volt component could be substituted in its place. If a 100 volt component wassubstituted, that would be acceptable because the component can handle up to 100 volts. Itwould be unacceptable if a 25 volt component were substituted instead. If 50 volts were appliedto a component rated for 25 volts, the component would not function properly and would likelybe damaged.The same rule applies when substituting wattage. To substitute a resistor rated at one quarterwatt, you would need to use one that would be capable of receiving a higher wattage – say onehalf watt – rather than lower, or one eighth watt.Another substitution may involve tolerance. Unlike voltage and wattage that substitute usinghigher numbers, when it comes to substituting tolerances, you must use a component of the samevalue with a lower tolerance. The lower tolerance is a more controlled and precise component.For example, the bill of materials description calls for a 5% tolerance. An acceptable substitutionis with a tolerance of 1%. One percent is considered a precision part. The operating range isnarrow and more controlled – so it is acceptable to use a 1% tolerance in place of the 5%.This program has presented the details of how to accurately read component color bands. We’vealso demonstrated how to calculate the value of resistors, capacitors and inductors.There’s been a lot of information presented – and you certainly don’t need to remember it all.What is important is to be able to use the methods shown in this video. That means using thereference sheets we provide to help you to decipher the color codes. By learning andunderstanding how to turn colors into numbers, you can take the mystery out of identifying thevalue and tolerance for these types of components.6